Tom is gone. Dan is going. Network news is in transition, all right, but to what? The departure of two iconic anchors--so well-known that first names suffice--obviously signals the end of an era. But that's neither as momentous nor as irrelevant as it's been made out to be.

As anchors, Tom Brokaw and Dan Rather were fixtures at their networks for most of a quarter century, longer than any of their predecessors. When they started in the early 1980s along with ABC's Peter Jennings, the news landscape was dramatically different. CNN was Ted Turner's wacky new idea; Fox was just a movie studio; and the Internet was known only to computer geeks. There were only three national newscasts, and most Americans chose to watch one of them.

My, how times have changed. Only 36 percent of American households tune in to the nightly news these days, according to Nielsen Media Research, about half as many as back then. Over the same period, National Public Radio's weekly audience has grown from 2 million to almost 30 million. The cable universe, from ESPN to CNBC, is crowded with information. In a watershed moment last summer, cable beat the networks for the first time ever, when more people watched the Republican National Convention on Fox News than on any broadcast channel. And more people now go online for content--news, information and entertainment--than for communication or commerce, according to the Online Publishers Association.

But contrary to some reports, network news is not dead, at least not yet. A combined audience of more than 26 million a night is nothing to sniff at, nor is the $100 million-plus in annual advertising revenue generated by each of the big three newscasts. No cable news program comes close.

Even that might not be enough to save the evening newscasts if the local affiliates really wanted to dump them, but so far there's no sign of rebellion in the ranks. "We see the nightly news as being relevant, maybe more relevant now than it has been in recent years, with national news at the top of the headlines every day," NBC affiliate board chief Terry Mackin told the Associated Press.

A closer look at who's watching the nightly news signals more trouble ahead, however. The average viewer is now over 55. Despite efforts to hold on to an audience by adding more health and lifestyle stories, the networks have continued to lose ground.

Any industry whose consumers are dying off needs to evolve or expire, and that message may finally be getting through. "People are going to have to look at news differently, and certainly we are," CBS chief Leslie Moonves says. The question is whether the networks will resort to more tinkering to keep the nightly news ship afloat, or whether they'll do what's really needed--a total overhaul.

At this point, it looks like they're just rearranging the deck chairs. NBC replaced one attractive white male anchor with another, younger model in Brian Williams, whose main contribution might be to lighten things up a bit in an attempt to attract younger viewers. "There are ways to find little moments of absurdity or humor in life, and we're going to try and find ways to do that," NBC News President Neal Shapiro told the New York Post, while insisting the news will remain "very serious." Now that's innovative. Pray tell, why would anyone choose a newscast with moments of humor when they can watch real comedy with moments of news on "The Daily Show"?

What network news can do better than anyone else in television is to add context and meaning to the day's events. Unlike their counterparts in local TV news, most network journalists still have the luxury of filing one well-produced story a day. If they can't tell us much that we don't already know, they should tell us something about the news that we haven't considered. And they should do it when we can watch, not just once a day at 6:30 p.m. when many of us aren't home. Keep a half-hour newscast on the air to serve the affiliates, but put a longer version on cable, repeat it and stream it online as well. A newscast that goes deeper than the headlines should have some shelf life, after all. Make it an easily accessible, dependable alternative to the nonstop shoutfests served up by the cable networks. If those channels aren't going to offer news most of the time, somebody else should.

Network news is not in imminent peril. It will survive as long as it keeps making money, but that doesn't mean forever. The nightly newscast needs to change or it will vanish. And if it just fades away as its audience ages, there won't be anyone left who misses it when it finally winks out.